![]() For example, in cerebral ischemia, elevated lactate is an early marker of tissue salvageable by thrombolytic therapy ( 6). Many other pathologic changes are associated with an increase in lactate. A robust technique for non-radioactive lactate imaging would, therefore, serve a dual role in cancer diagnosis and in detection of tumor therapeutic response. and radiotherapeutic ( 5) response in animal models. Further, a decrease in lactate level has been shown to correlate strongly with chemotherapeutic ( 2– 4). Therefore, imaging lactate can potentially provide the same diagnostic information as FDG-PET for tumors without the need for radioactivity or for any exogenous probes. Due to this loss of efficient ATP production by the Krebs cycle, glucose consumption is increased, and the increased uptake is measured by 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) studies of tumors ( 1). For example, tumor cells exhibit enhanced glycolytic metabolism under aerobic or anaerobic conditions as part of the malignant phenotype, increasing local lactate levels. However, in many disease states and under certain physiologic conditions, increased lactate is observed. Lactate is the product of anaerobic glucose metabolism, normally only produced in small quantities in vivo in limited cell types, under certain conditions. In conclusion, the HDMD-SelMQC-CSI sequence is demonstrated on a phantom and in two lipid-rich, clinically relevant, in vivo conditions. As a test of SelMQC sensitivity, a thigh tourniquet was applied to a normal volunteer and an increase in lactate was detected immediately after tourniquet flow constriction. The elevated lactate signal coincides with the T 2-weighted image of this tumor. To demonstrate clinical feasibility, a 5 minute lactate scan of a patient with a non-Hodgkin's lymphoma in the superficial thigh is reported. An analysis of quantum selection gradient duration and amplitude effects on lactate and lipid signal is presented. This is followed by 1cm 3 resolution lactate imaging with detection to 5 mM concentration in 20 minutes on a 3T clinical scanner. Hadamard slice selection is explained and demonstrated in vivo. We implemented a 3D SelMQC version with Hadamard slice selection and 2D phase encoding (HDMD-SelMQC-CSI) on a conventional clinical MR scanner. ![]() The selective homonuclear multiple quantum coherence transfer (SelMQC) technique offers a method for distinguishing lipid and lactate resonances. Lactate is an important metabolite in normal and malignant tissues detectable by NMR spectroscopy however, it has been difficult to clinically detect the lactate methyl resonance because it is obscured by lipid resonances. ![]()
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